Prejunctional actions of muscle relaxants: synaptic vesicles and transmitter mobilization as sites of action

C Prior, L Tian, J Dempster, I G Marshall

Research output: Contribution to journalLiterature review

22 Citations (Scopus)

Abstract

Nicotinic antagonists such as tubocurarine affect acetylcholine release from motor nerve terminals at the neuromuscular junction. Electrophysiological studies comparing the prejunctional actions of tubocurarine to those of vesamicol and vecuronium have been used to provide an insight into the mechanisms involved in the prejunctional effects of tubocurarine-like compounds. The observed prejunctional actions of tubocurarine can be accounted for by a model in which the compound has two separately identifiable effects on the nerve terminal. At low frequencies of nerve stimulation tubocurarine augments acetylcholine release while at high frequencies of nerve stimulation tubocurarine depresses acetylcholine release. Both of the effects of tubocurarine on acetylcholine release are a consequence of a change in the number of quanta within the nerve terminal immediately available for release upon nerve stimulation. On the basis of our experimental observations, we suggest that the two prejunctional effects of tubocurarine are mediated through two pharmacologically distinct prejunctional nAChRs.
Original languageEnglish
Pages (from-to)659-666
Number of pages8
JournalGeneral pharmacology
Volume26
Issue number4
DOIs
Publication statusPublished - Jul 1995

Keywords

  • animals
  • humans
  • central muscle relaxants
  • neuromuscular junction
  • neurotransmitter agents
  • presynaptic receptors
  • synaptic vesicles

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